Heating and refrigerating process and apparatus



Feb. 9, 1943. R. ESNAULT-PELTERIE 2,3

HEATING AND REFRIGERATING PROCESS AND APPARATUS Filed Oct. 9, 1939 5Sheets-Sheet 1 INVENTQR fa-4M1 BY ATTORNEYS 1943- R. ESNAULT-PELTERIE2,310,520

HEATING AND REFRIGERATING PROCESS AND APPARATUS Filed Oct. 9, 1939 5Sheets-Sheet 2 INVENTOR -61: QM. 1,544 .5

BY ATTORNEY 5 1943- R. ESNAULT-PELTERIE- 2,310,520

HEATING AND REFRIGERATING PROCESS AND APPARATUS Filed Oct. 9, 1939 5Sheets-Sheet 3 INVENTOR W gM-w IETTORNZS 1943' R. ESNAULT-PELTERIE 20HEATING AND REFRIGERATING PROCESS AND APPARATUS Filed Oct. 9, 1939 5Sheets-Sheet 4 INVENTOR W MW ATTORNEYS 1943- R. ESNAULT-PELTERIE ,310,5

HEATING AND REFRIGERATING PROCESS AND APPARATUS Filed Oct. 9, 1959 5Sheets-Sheet 5 INVENTOR ma muwmrm ATTORNEYS Patented Feb. 9, 1943HEATING AND REFB'IGERATING PROCESS ANDAPPARATUS Robert Esnault-Pelterle,Boulogne-Billancourt, France; vested in the Alien Property CustodianApplication October 9, 1939, Serial No. 298,570 In Switzerland October10, 1938 23 Claims.

The present invention relates to an improved process for heating andrefrigerating according to the principle of the thermo-pump andapparatus for use in carrying the invention into efiect.

The process forming the subject matter of the present invention has moreparticularly been conceived as an improvement of the thermodynamicheating and cooling processes as applied to inhabited spaces and moreparticularly to railway cars, but the invention can equally as well beadapted to other purposes, such as the manufacture of ice, for instance.

It has been known for a long time that a Carnot cycle comprised betweentwo absolute temperatures T and To, if it operate in the sense of amotive force, has an efficiency:

- T-T R= T 1 (1) ing work, it separates, so to speak, a certain .of heatproduced and absorbed.

Therefore, if from a purely utilitarian point of view the efficiency ofsuch an engine be called the thermal efiiclency, .the quotient of theamount of heat or cold obtained by the amount of work that had to bespent to produce it, then these efliciencies for the heating machinewill be:

T ph= and for the cooling or refrigerating machine:

r= Z ;:l

the difference between the two efliciencies is always equal to unity.

It is, therefore, seen that theoretically, and by reason of the smalldifferences of temperature that have to be produced to heator coolinhabited spaces in respect to To, which is always of the order of 273absolute, (0 0.), there is nothing in theory to event obtaining amountsof cold and especiall of heat, that are greatly superior to the workfurnished, and even superior to the quantity of heat initiallyexpendedin the fuel actuating the steam engine prime mover or theinternal combustion engine or other prime mover.

Unfortunately, it is a long way from theory .to practice, and themechanical efliciency of the engines used intervenes in such a form, inthe actual operation, that it decreases the advantage to a considerabledegree, and can even reduce it to zero if very special precautions arenot taken to guard against it. 1

Heretofore, for a considerable time machines of this type have been,used for the production of artificial cold, without however having ledto any apparently notable industrial development, since Lord Kelvinfirst published the principle of the thermo-pump.

According to theory the working fluid can be of any kind whatever; untilnow, the industry uses only highly compressible fluids, gases or vapors.

The inventor of the present invention has conceived the idea to correctthis defect of the gases by using high pressures.

It is well known that according to the kinetic theory of gases, thepressure of a gas is, at a given predetermined pressure, proportional tothe number of molecular impingements per unit of time upon a unit of thewall surface. Now, the heat exchange increases proportionally to thisnumber of impingements or shocks. Consequently, by using high pressures,it is possible to obtain a very rapid heat exchange, notwithstanding theworking fluid being used, formed at least partially of a gas, and thiscan be attained with heat exchange surfaces of sufliciently reduceddimensions; and this in its turn is the cause of reduced first costs ofthe plant, and a considerably increased efliciency, by reason that, dueto the rapidity of the heat exchange between the compressed gas and thewalls of the heat exchanger it is possible to reduce the diflerence oftemperature on the two surfaces of the heat exchangers.

The improved heating and cooling or refrigerating process according tothe present invention is characterized in that working fluid comprisinga gaseous substance, is caused to pass through a thermodynamic cycle,the low pressure of which is at least equal to 20 kg./cm. (about 284lbs. per sq. in.)

The apparatus for carrying the present process into effect ischaracterized in that it comprises means to cause a working fluidcomprising a gaseous substance, to pass through a thermodynamic cycle,the low pressure of which is at least equal to 20 kgJcmF.

Theoretical analysis of the principle of the present invention has shownthat-an interesting thermal efliciency can only be obtained when themechanical efllciency -of the apparatus is equal to or even 96%; this isnot an easily realizable condition. y

In the present description, two means only are described which complywith such-requirement,

and these are then of considerable importance:

The star disposition of the main pump and fluid motor on the same crankresults in opposing the efforts of the diflerent pistons so that theresulting effort is very much smaller than the sum or the composingones.

The use of a lower pressure at least equal to 20 atmospheres and theapplication of the said pressure on the external faces of the pistonsre- .duces the diiference of pressures on the pistons to the possibleminimum and accordingly reduces to the possible minimum the strains onthe connecting rods and bearings and the friction which takes place intheir articulations.

Correlatively the use of such a pressure renders 4 acceptable the volumeand weight of the apparatus, which otherwise, would be prohibitory andsimilarly for the sections at the valves in which the difierence ofpressure becomes proportionally very slight when working at 20 atms.whereas it would be prohibitory upon working at 1 atm.

In addition to this the use of high pressures presents the advantage ofimproving the heat transmission in the heat exchangers.

The star disposition of the main pump and fluid motor on the same crankresults in opposing the efforts of the different pistons so that theresulting strain is very much smaller than the sum of the composingones.

In order that the invention may be clearly understood and readilycarried into efiect reference is made to the accompanying drawings whichshow diagrammatically and by way of example heating and refrigeratingapparatus in accordance with the present invention.

Figure 1 is a diagram of a complete apparatus intended to illustrate thecircuits by means of which the working fluid passes through thedifferent members or parts of the apparatus.

Figure 2 shows 8 sections along the 8 parallel planes a, b, 0, cl, e,grand h (of Fi 1) of the multiple way plug cock serving to modify theconnections between the variou members of the apparatus when the latteris intended to be changed over from a heating to a cooling orrefrigerating plant, and vice-versa.

Figure 3 is a cross section of the motor-pump unit.

Figure 4 is an axial section, along the line 4--4 of Figure 3 of themotor-pump unit.

Figure 5 represents the profile of a cam to control the admission intothe motor cylinders of the motor-pump unit according to Figures 3 and 4.

Figure 6 represents the profile of a cam to control the escape orexhaust from the motor cylinders appertaining to the motor-pump unitaccording to Figures 3 and 4.

Figure 7 is a diagram of a control arrangement and is intended toexplain the ifect produced by the change of position of the camsaccording to Figures 5 and 6.

Figure 8 is a detailed view showing in section a manometric device foruse in controlling the operation of an auxiliary pump intended tocompensate the difference of pressure of the intake side of themotor-pump unit shown in Figures 3 and 4.

Figure 9 is a detailed view showing, in section, another manometricdevice to control the automatic change of position or shift of the camsaccording to Figures 5 and 6, for correcting the differences of pressureon the discharge side of the motor-pump unit according to Figures 3 andFigure 10 is a diagram of the control apparatus for automatic regulationof the intake and discharge pressures of the main pump I I.

General description of fluid circuit The apparatus comprises a normallyclosed path in which the working fluid circulates. The fluid circuit isshown in Figure 1 and is adapted alternatively either to heat thechambers IS, IS and IT or to cool them. Whether the apparatus is adaptedto heat or to cool the chambers IS, IS and I1 depends upon the positionof handle 24. Movement of handle 24 rotates core 23b in such manner thatthe eight valves formed by the drillings therein are shifted intoposition so as to reverse the piping connections. At the same time theelectrical switch I45 (Figure 10) is changed to its opposite position toreverse the control mechanism.

When the apparatus is used for heating the chambers I5, I5 and II, thecycle of the compressed fluid within the closed circuit is shown byarrows withsolid shafts in Figure 1 and is as follows:

(1) The fluid passes through the compressor I I Where its pressure andtemperature are raised;

(2) The highly compressed fluid passes through coils I2, I3 and I4 whereit gives up heat in counter-current manner to air entering chambers 15,I6 and I1;

(3) The fluid then passes to the heat exchanger 22 where it gives upadditional heat by movement in a counter-current manner with respect tofresh air being intaken from the outside atmosphere, and later to bedischarged into the chambers I5, I6 and I1;

(4) Having lost most of its heat but relatively little of its highpressure, the fluid then passes to the fluid motor 20 where it isexpanded to a lower pressure, the energy derived being used in part todrive the compressor l I (5) The fluid then passes to the heat exchangerI9, positioned in the outside atmosphere or in the water of a lake,etc., where it acquires heat;

(6) The fluid then passes to the heat exchanger 2| where it extractsadditional heat from the vitiated air being expelled to the atmospherefrom the chambers I5, I6 and I1, moving in countercurrent relation withrespect thereto; and

'(7) The fluid then passes to the intake side of compressor II.

When the apparatus is used for cooling the chambers I5, I6 and I1, thecycle of the compressed fluid within the closed circuit is shown byarrows with broken shafts in Figure l and is as follows: v

(1) The fluid passes through the compressor I I where it reaches ahigher temperature;

(2) The fluid then passes to the heat interchanger I9 where it gives of!heat to the outside atmosphere, or to water in a lake or otherwise;

(3) The fluid then passes to a heat exchanger 22 where it moves incounter-current relation to the vitiated air being discharged fromchambers I5, I6 and I! to the atmosphere, and where it gives up moreheat;

(4) The fluid then passes to the fluid motor 20 where it is expanded andfalls in temperature, the energy derived being utilized in part to drivethe compressor I I (5) The fluid then passes through the coils I2, I3and I4 where it moves in counter-current relation to the air beingintroduced into the chambers I 5, I6 and I1 and absorbs heat therefrom;

(6) The fluid then passes to the heat interchanger 2I where it moves incounter-current relation to air being drawn in from the outsideatmosphere, and destined for transmission to the chambers I5, I6 and I1,and where the fluid A main pump compressing the working. fluid Iadiabatically, in order to increase its temperature.

At least one heat exchange member wherein,

this temperature is lowered according to an approximately isobar regime.

A fluid motor, wherein the working fluid emerging from the heatexchanger expands adiabatically (by producing work, which is recoveredfor driving the pump) its temperature decreasing co-relatively.

At least one heat exchange member, where the temperature of the workingfluid again increases under an approximately isobar regime, the workingfluid then returning to the main pump, and beginning the same cycleagain.

An auxiliary or external motor (in this case electric) producing thedifference between the power absorbed by the pump, and that recoveredfrom the fluid motor, that is to say, producing the mechanicalequivalent of the difference of heat absorbed and given off by the fluidduring its flow through the heat exchanging organs and to make up forthe mechanical losses.

If the problem is to heat a room or space, the radiator will be arrangedin this room or space, and a heat absorbing coil will be placed in amedium which may for instance be the ambient '49 air, or water from ariver or a lake.

If on the other hand it is intended to cool a room or space, that is tosay to produce cold, then the cooling coil is placed in this room orspace, and a heat dissipating coil may be placed in a medium such as forinstance the surrounding air, or the water from a river or lake.

General arrangement of the apparatus A general arrangement of theapparatus represented in Figure 1 uses air as a working fluid, andcomprises the following parts; a main pump II, which compresses theworking fluid; heat exchanging members I2, I3 I I which operate eitheras radiators or as cooling coils and which are arranged in chambers orcompartments I5, I6, I! respectively of a space to be heated or cooledor refrigerated. Such space might for instance, be a railway carriage ortruck, diagrammatically indicated at I8 in Figure 1. Each chamber orcompartment may be fitted with a A heat exchanger 2|, wherein theworking fluid gives up heat to the air of aeration (conditioning air) ofthe chambers I5, I6 and II or abstracts heat from this air, according tothe case.

A second heat exchanger 22, similar to the heat exchangers 2|.

A multiple way plug cock 23, comprising a series of 8 plugs connectedintegrally and simultaneously operable by means of a hand lever 24common to all and of which Figure 2 shows the cross sections at 8positions designated by a, b, c, e, f, U, h in Figure 1. The plug cock23 comprises a hollow tube 23a provided with openings in which thevarious piping connections may be secured, and a core 23b rotatablyfitting therein and having drillings therein adapted to register withthe said openings in the manner shown in the drawings. For example, inFigure 2, section a, the shaft-drillings are arranged at that point toprovide inter-communication between pipes I86 and I8! when the shaft isin the position shown; when rotated 45 in a clock wise direction pipesI81 and 209 are thereby brought into communication.

An auxiliary pump 25 in communication at 26 with the atmosphere and withthe low pressure side of the main pump II.

A safety valve 2 I2 placed on the high pressure side of the main pumpII.

An aeration-air inlet 21 disposed at the lower part of the heatexchanger I2 in such manner, that the air issuing from 21 comes intocontact with the heat exchanger I2 before entering into the chamber I5.

Corresponding inlets 28 and 29 for aerationair arranged similarly at thelower parts of the heat exchangers I3 and I4 respectively.

A suction funnel 30 for the escape of aerationair from the chamber I5.

Similar suction funnels 3|, 32 placed at the top parts of the chambersI6 and II respectively.

A blower 33, forcing air from the outside, after it has passed in one ofthe two heat exchangers 2|, 22 as will be described below, into thechambers I5, I6 and H.

A second blower 34 drawing air from the chambers I5, I6 and I I, andforcing it outside after forcing it to pass through the other of theheat exchangers 2 I, 22.

A manually operable plug cock 35 to regulate the heating of the chambersI5, I6 and I! or the cooling thereof, while allowing a regulatablequantity of the working fluid to be short-circuited, which otherwisewould pass through the heat exchangers I2, I3 and I4.

Connecting pipes between the parts above mentioned, which will behereinafter described in detail.

The apparatus comprises, besides the parts and the pipingdiagrammatically shown in Figure 1, a motor, the housing of which isshown at 36 in Figure 4, which receives energy from an external source,in order to enable it to supply the difference between the powerabsorbed by the main pump II, and the energy recovered by means of thecompressed fluid motor 20. The motor 36 is supposed in this example tobe an electric motor. It could of course be an internal combustionengine or a hydraulic motor for example.

Finally the apparatus further comprises control or regulating memberswhich are hereinafter described with reference to Figures 4 to- 10.

Motor-pump unit The motor-pump unit shown in Figures 3 and 4 comprisesthe pump I and the fluid motor 20, as well as an electric motor of whichonly the housing or frame is shown at 36. It should be clearlyunderstood that although Figure 3 shows six cylinders any other suitablenumber of cylinders may be used, for example II] in one block. To attainthe desired high mechanical efllciency the compressor and. pumpcylinders should be diametrically opposed to each other and, to reducevibration and wear, compressor cylinders should be arranged inalternation and pump cylinders should be disposed between the compressorcylinders. This arrangement requires the use of not less than sixcylinders to avoid dead center stalling points, although eight or anyeven number greater than eight may be used. The pump comprises threeradial cylinders 31, 38 and 39, arranged at 120. The motor comprisesthree cylinders, 40, 4| and 42 similarly arranged star-fashion at aspacing of 120 between each of them, and which can be staggered at 60 inrespect of the pump cylinders.

A piston 43 reciprocates in each pump cylinder. In each motor cylinderreciprocates a piston 44. One of the pistons 43 is connected to a crankpin 46 by means of a master connecting rod 45. Pivotally connected tothe master connecting rod 45 are five connecting rods 41 three of whichare in the present case pivotally connected to the pump pistons and theother two to the motor pistons. On the common shaft 48 (which is assumedto revolve at the speed w) of, the motorpump unit having the motor pumpcylinders alternatively arranged star fashion, is mounted the electricmotor arranged in its housing 36.'

A counter-weight 49 is provided on the shaft 48. The head of each pumpcylinder 31, 38 and 39 comprises a block 49 of heat insulating materialsuch as synthetic resin for example, wherein an automatic compressionvalve 50 is mounted, which is forced against its seat by a spring 5|.Each valve 50 controls the passage between the interior of therespective pump cylinder of the pump, and a heat insulated pipe 52. Thethree pipes 52 lead to a common collector 53. The springs 5| areprovided in order that the valves 50 should open automatically, as soonas the pressure in the respective cylinder exceeds the pressure existingin the pipes 52-. Each piston 43, 44 is provided on its internal fiatface in respect of the cylinder with a heat insulating plate 54, 54respectively. An automatic valve 55 is arranged in each piston 43; it isacted upon by a spring 58 tending to hold it oil its seat. Two leverarms 51a, pivoted near their midpoints on pivots secured to the piston,are pivotally secured upon a common pin 51b secured to the stem of thevalve 55. Counterweights 51 are mounted upon the opposite ends of saidlevers. Valves 55 are slightly underbalanced so that they have atendency to open at the end of the outward stroke, but are preventedfrom so doing by the excess pressure of the compressed and expelled airover that one which prevails in the crank-case until the piston comesback,

causing a sufllcient fall in the pressure prevailing within thecylinder. Likewise, at the end of the inward stroke, valves 55 have aslight tendency to close, but are prevented from so doing by beingsucked toward the cylinder until the piston starts its outward stroke,thereby Each of the cylinders 40, 4| and 42 of the motor is providedwith a cylinder head 58 made of heat insulating material, and therein ispositioned a controlled admission valve 59, and a controlled exhaustvalve 60. Each valve 59 controls the communication between a heatinsulated pipe 6| and the respective cylinder. All the pipes 6| lead toa common collector 62 (Figure 4). Each valve 69 controls thecommunication of one of the cylinders with a heat insulated pipe 63. Thethree pipes 63 lead to a common collector 64 (Figure 4). The valves 59and 60 are held on their seats by springs, which are shown in Figure 3,and are indicated by I03 for the valves 59 and by I04 for the valve 60.These valves are operated as hereinafter described.

The open ends of the six cylinders shown in Figure 3 are connected to acommon chamber 65 (Figure 4) wherein the six connecting rods, the crankpin 46, and the counterweight 49 move. This chamber is formed by theassembly of the two halves 66 and 61 of the housing, which are securedtogether by bolts (not shown) said bolts pass through lugs 68, of whichonly those of the half 61 are shown in Figure 3. The half 66 (Figure 4)of the housing is provided with a flange 69, which serves to secure theunit, for instance under the floor of a carriage or truck. The interiorof the chamber 65 is in communication with a heat insulated pipe 10. Thecollectors 53, 62 and 64 (Figure 3) are each connected to a heatinsulated pipe, denoted respectively by 12, 13. A ball bearing 14,mounted in the interior of a hub 15 of the member 61 of the housingserves as a bearing or support for the shaft 48. A cup leather 16, heldin position by a disc 11 screwed into the hub 15 ensures the 53, 62 and64 are arranged on the periphery of the motor housing 36, and aresurrounded by a covering of heat insulating material 8 I.

Advance and retard of the valves The motor 20 which can be seen indetail in Figures 8 and 41s a piston or reciprocating motor with itscylinders arranged star fashion. Considering that in this case we haveto deal with a compressed fluid motor with its cylinders, the workingfluid is admitted and exhausted once per each revolution of the motorinto and from each cylinder. The consecutive cylinders 40, 4| and 42therefore work one after the other, in the order corresponding to thedirection of rotation of the motor (see arrow 10 in Figure 3).

In the same manner as in the case, which is similar to this one, of theknown distributions in 4 cycle explosion motors with an odd number ofcylinders arranged in star fashion, it is possible to use one single camfor the control and actuation of all the inlet valves, and a further camfor the exhaust valves of a compressed fluid motor with its cylinders ofthe type shown. To that end it is possible to use two cams, both turnin;either in the direction of the rotation of the motor or in the oppositedirection.

Consider in the first instance the case, where the cams rotate in theopposite direction to the direction of rotation of the motor, with itscylinders which corresponds to the embodiment shown in the drawing.

Consider also the generic case of a compressed fluid motor of Ncylinders, N being an odd number and call a the angle zw/N which theaxes of two consecutive cylinders form between them.

Take as a reference datum on one cam, the admission cam for instance, acam boss and let it be assumed that said boss is opposite to cylinder i.

Between two successive admissions, for instance between the admission tocylinder No. 1

and to cylinder No. 2, since the cylinders receive a the fluid in theorder of their numbers, the motor will have turned by an angle a. Atthis moment the following boss of the cam under consideration must beopposite to cylinder No. 2. If it be admitted that the cam has turnedthrough an angle (:c) then this second boss forms with the first bossconsidered, an angle Now whatever the values of N and a: may be, it isevident that at the end of one revolution of the motor, it must be thesecond boss of the cam that replaces the first in its functions vis-aviscylinder No. 1.

It is therefore evident that the angle (a+:c) is determined by tworequirements, viz:

(1) It must be a fraction of 211-.

(2) The cam must, at the end of one revolution of the motor, haverotated by the amount of 5. Now if in one revolution of the motor, thatis 21r, the cam rotates by p, t en the angle :1: by which it has rotatedwhile the motor has 'only rotated by a is such that B 2 1r & 33" a a Nwhence E "*N and as E B 21r Therefore in the case where the cam rotatesin the opposite direction to that of rotation of the motor, the cam musthave (N -1) bosses, and as it must revolve by 21r/N1-Wh11e the motorrevolves by one revolution, i. e. by 21r, its speed must be (N1) timessmaller than that of the motor.

If on the other hand it be desired that the cam should rotate in thesame direction of rotation as the motor, Equation 1 only would have tobe modified, and would become We would still have which would give Itmay be deduced therefrom that, in the case of the cam rotating in thesame direction as the motor, it would be necessary to provide (N+1)bosses on it and rotate it at (N+1) times the speed of the motor.

In the embodiment shown in Figures 3 and 4. the motor comprises threecylinders, 48, 4| and 42, if it .be desired that both the admission camand the exhaust cam rotate in the opposite direction to that of themotor, two bosses will have to,

be provided on each of them, and they will have to rotate at a speed ofrevolution equal to half that of the motor shaft.

In the embodiment shown, each admission valve 581s controlled andactuated by a forked tappet lever 82 (Figure 3) on which one end of arod 83' acts'(Figure 4) On the other end of the rod 83 a roller 84 isrotatably mounted, which follows the curve of the common admission cam85. A strong spring 88 arranged on the rod 83 causes the roller 84 to bepressed on and to follow the contact curve of the cam 85. Each exhaustvalve 68 is controlled and actuated by a lever 81 acting as a tappet, onwhich one end of a rod 88 acts, a follower roller 88 rolling on a commonexhaust cam 98 being rotatably mounted on the other end of the said rod.A strong spring 9| disposed around the rod 88 causes the roller 88 to beconstantly applied against the common cam 88.

Figure 5 shows the .profile of the admission cam 85 rotating at half theangular velocity and in the opposite direction of that of the shaft 88.On this cam the two points corresponding respectively to opening andclosing of the admission in the course of a first revolution of themotor having been designated by 0A1 and FAi; 0A2 and PM designate thecorresponding opening and closing points of admission during the courseof the next revolution.

Figure 6 shows the profile of the cam 98 for the exhaust 0E1 and FE].indicate respectively the points corresponding to opening and closin ofthe exhaust during the course of a first cycle of the motor, 0E2 and FE:indicating the two corresponding points of opening and closing of theexhaust respectively, in the course of the following revolution.

In Figure 7, 0A, FA, OE, FE, designate respectively opening of theadmission, closing of the admission, opening of the exhaust, and closingof the exhaust of any one of the motor cylinders, relatively to theposition of the crank pin 48 (circular diagram) and of the correspondingpiston (rectilinear projections) in considering one revolution of thecrank pin, in the case of normal admission.

For reasons that will be hereinafter mentioned, it is desirable to beable to increase or decrease the degree of admission to the cylinders,that is to say, that fraction of the piston stroke during which theadmission takes place, without thereby causing any sensible variation ofthe exhaust. This is efiected :by acting on the cams 85 and 88 in such amanner, that the four points 0A, FA, OE and FE, shall be subjected to anequal angular displacement. When the degree of adtherefore take place inthe direction of the arrow 92, in such manner that the cams operatelater on the follower rollers, than is the case with normal admission.In the case of a decrease of the degree of admission, the camdisplacement will be effected in the direction of the arrow 93, in suchmanner, that the bosses on the cams act earlier on the follower rollersduring the revolution than is the case with normal admission.

It will be noticed that in the projection on the path of the piston itis only the point FA that has undergone a sensible linear displacementby reason of these angular displacements. The points DA, E and FE do infact only undergo an insignificant linear displacement, because of thefact, that they always remain in the immediate proximity of the deadcentres PMH and PMB.

The cams 85 and 90 are shaped on the periphery of a crown 94, rotated athalf the speed of that of the shaft 48, and in the opposite directionthereto, by means of a differential gear permitting the angulardisplacement or these cams to be effected. The aforesaid differentialgear comprises a gear wheel 95 (Figure 4) keyed on the shaft 48,planetary gears 96, the diameters and the number of teeth of each ofthem being equal to half the diameter and half the number of teeth ofthe wheel 95, and which mesh with the gear wheel 95 and with internalgear teeth 91 provided on the member 94. The diameter and the number ofteeth of the gearing 91 are equal to twice the diameter and number ofteeth of the wheel 95. v

The crown 94 is adapted to run freely on the hub or boss I5 by means ofball bearings 98.

The shafts 99 of the planetary gears 96 are mounted by means of rodsI00, on a worm wheel IOI, loosely mounted on the shaft 48, and adaptedto be angularly displaced by means of a worm I02.

It is evident that by turning the worm I02 by a certain amount in onedirection or the other, this determines, by means ,of the differentialgearing, an advance or retardation of the action of the cams on thefollowers 84 and 89 relatively to the position of the crank pin 46.

It clearly appears from Figures 3 and 4 that the angular shift of thecams in the direction of a retardation in the admission, must beeffected by rotation the worm wheel IOI in the direction of rotation ofthe motors (arrow I05, Figure '7), since a retardation of the cam actionon the followers is thereby obtained. In order to obtain an advance inthe admission, it will therefore be necessary to turn the worm wheel INa certain amount in the opposite direction.

Regulating apparatus (Figure 10) The regulating apparatus according toFigure 10 comprises a manometric device I06, shown in section in Figure8, and another similar manometric device I01 shown in section in Figure9. These devices may be of any suitable type known per se. The functionof these devices is to maintain the low pressure and the high pressureof the pump II at predetermined levels. r

The manometric device I06 comprises a cylindrical chamber I08, in theinterior of which there is arranged an undulated metallic tube I09, ofwhich the end which extends into the interior of the chambe I08 isclosed by a head I00 carried by a rod I I I which extends outwardly ofthe chamber I00 and the tube I09. The top end of the tube I09 issoldered on to the head H0 in such manner that there is no communicationwhatever between the interior of this tube and the interior of thechamber. At its lower end the tube I09 is open, and is soldered to aconical annulus I I2 fitted into the mouth of the chamber I08 so as toclose it hermetically. The conical annulus I I2 is held in place by acap I I3 screwed on to the wall of the chamber I00. A spring II4,slipped over the rod III abuts at one end against the head H0, and atthe other end against an adjustment bolt I I5 provided with a knurledhead H6 which can be locked by means of a lock nut Ill. The rod IIIpasses loosely through the nut II6, so that the interior of the tube I09is constantly at atmospheric pressure. The spring II4 tends to cause thehead IIO to penetrate further into the chamber I08, than the tube I09will permit. The interior of the chamber I00'is in communication with atube I I9 connected to the pipe I0 (Figure 10). Thus the interior of thechamber I08 is at the pressure existing in the low pressure side of thepump II, that is to say at the pressure existing in the crank or gearhousing (chamber of the motor-pump unit shown in Figures 3 and 4. Itwill be readily understood therefore, that, for a given adjustment ofthe bolt II5 the rod III occupies a position that is a function of thepressure on the intake side of the pump.

The manometric device according to Figure 9 is similar to the manometricdevice according to Figure 8. It diifers therefrom by the fact, that thebolt 5', otherwise identical with the bolt II5, instead of beingprovided with a knurled head to permit of manual adjustment, is designedto be actuated through a spline 9c by a worm wheel II9 which meshes witha worm I20. It further diifers also by reason of the fact that there isno lock nut III. The manometric device I01 is connected by means of atube I2I to the pipe II (Figure 10) wherein is the working fluid at apressure equal to the discharge pressure of the pump II. It will beunderstood that the rod III of the manometric device I0'I normallyoccupies a position which is a function of the pressure on the dischargeside of the pump II.

The rod III of the manometric device I06 actuates a comutator switch I22by means of a lever I23 rigidly mounted on a shaft I24. The commutatorswitch I22 is provided for the pur pose of controlling four contactsI25, I29, I21 and I28. In its normal position the commutator switchleaves the four contacts open. This normal position corresponds to theposition occupied by the rod III of the manometric device I06, when thepressure on the intake side of the pump is equal to a predeterminedvalue, for which the manometric device I05 has been previously set. Whenthe pressure on the intake side of the pump exceeds the value aspredetermined, the rod III moves downwards, thereby causing thecommutator switch arm I22 to turn in a clockwise direction (as seen inFigure 10) thus closing the contacts I21 and I28. 0n the other hand,when the said pressure of the pump II drops below the above mentionedpredetermined value, the rod III ascends moving the commutator switcharm I22 in an anti-clockwise direction (as seen in Figure 10) thuscausing the contacts I25 and I26 to be closed.

The rod III' of the manometric device I0'I actuatesa commutator switchI22 by means of a lever I23 rigidly mounted on the spindle I24. Thecommutator switch I22 is provided to control the contacts I25, I26, I21and I28. In its normal position this switch does not affect the saidfour contacts and they remain open. This normal position, corresponds tothe normal position occupied by the rod III of the manometric deviceI01, when the pressure on the discharge side of the pump II is equal toa predetermined value, according to the position occupied by the boltthat is to say, according to the adjustment at the time being of themanometric device I01. When the said pressure of the pump II exceedsthis value, previously determined, the rod III moves downwards, therebyrotating the commutator switch arm I22 in a clockwise direction, (asseen in Figure thus closing the contacts I21 and I28. If, on the otherhand, the pressure on the discharge side of the pump I I drops below theabove mentioned predetermined value, the rod I I I ascends, therebyrotating the switch arm I22 in an anticlockwise direction (as seen inFigure 10), thereby causing the contacts I25 and I26 to be closed.

The worm I20 is an integral part of the shaft of a small electric motorI29. In the arrangement shown, the motor I29 is of the reversible type,such reversal being effected by reversing the supply current at itsterminals I30, I30.

Two relays I3I, I32 and a reversible switch I46 control by means oftheir contacts the running of the motor I29 in one direction or theother.

It will be seen from Figure 10 that for the position of the reversingswitch I46 shown, the contacts I33, I34 of the relay I 3I are connectedto the supply mains I35 and I36 in such manner, as well as to theterminals I30 and I30 of the motor I29, that when this relay isenergized and its contacts are closed, the mains I35 and I36 areconnected to the terminals I30 and I30 of the motor I29, and that thelatter will rotate in a direction to efiect the screwing in of the bolt5' by reason of the rotation of the worm I20 and the worm wheel I9. Itis also evident that for the same position of the reversing switch I46,the contacts I31, I38 of the relay I32 are connected to the supply mainsI35, I36 and to the terminals I30 and I30 of the motor in suc mannerthat, when the relay I32 is excited, its contacts consequently close,and the mains I35 and I36 are respectively connected to the terminalsI30 and I30 of the motor I29, which will then rotate in a directionopposite to the previous direction of rotation, that is to say, in adirection to efiect the unscrewing of the bolt II5 by reason of thereversed rotation of the worm I20 and the worm wheel II9. If thereversing switch is in the other position, the action of the relays I3Iand I32 is reversed in so far as the connections of the terminals of themotor I29 to the supply terminals are concerned, as can be easily seenfrom the diagram. The reversing switch I46 occupies the position shownwhen the installation is used for heating purposes. In case it is usedfor cooling the reversing switch occupies the other position.

The contacts I25, I26, I21 and I28 serve for the purpose of controllingthe supply of current from the mains I35, I36 to the terminals I39, I40of another small electric motor I4I.

It will be seen from Figure 10, that these four contacts are connectedin such manner that, when the contacts I25 and I26 are closed, the mainsI35 and I36 are connected respectively to the terminals I40 and I39, andthat when the contacts I21 and I28 are closed, the mains I35 and I36 areconnected to the terminals I39 and I40 in the reverse manner. In thearrangement shown, the motor MI is of the reversible type and can bereversed by reversing the current supply. The motor I4I drives theauxiliary pump 25. This auxiliary pump is connected on one side to theatmosphere at 26 as already mentioned and on the other side, by means ofa pipe I42 to the pipe 10 on the intake side of the main pump I I. Themotor MI is provided for the purpose of driving the auxiliary pump 25 ina direction to effect the compression of the ambient air in the pipe I42and thus on the intake side of it now sucks the air from the intake sideof the pump II, and forces it out into the atmosphere. The auxiliarypump 25 automatically cuts oil communication between the atmosphere andthe pipe I42, when not in action.

The contacts I25, I26, I21 and I28 control the supply of current fromthe mains I35, I36 to the terminals I39, I40 of a small electric motorI43. These four contacts are connected in such manner that, when thecontacts I25 and I26 close, the mains I35 and I36 are connectedrespectively .to the terminals I40 and I39, and that when the contactsI21 and I28 close, these mains I35 and I36 are connected respectively tothe terminals I39 and I40 of the motor I43. This motor is also of thereversible type and can be reversed by reversing the current flowingthrough it. The motor I43 actuates the worm I02. The motor I43-servesthe purpose of rotating the wor I02 in a direction corresponding to adisplacem nt of the worm wheel IM and of the shafts 99 of the planetarygears 96 (Figures 4 and 10) in the direction of the arrow 93 (Figure 7)thus causing a decrease of the admission, when the contacts I25 and I26close by reason of a drop in the discharge pressure of the pump II belowthe value determined according to the actual position of the regulatingbolt H5. The motor I43 causes the worm I02 to rotate in a direction toeffect a displacement of the shafts 99 (Figures 4 and 10) in thedirection of the arrow 92 (Figure '1), which means an increase ofadmission, when the contacts I21 and I28 close by reason of a rise ofthe discharge pressure of the pump II above the value corresponding tothe momentary position of the regulating nut 5' of the manometric deviceI01.

From the preceding description it is evident that:

When the pressure on the intake side of the pump I I drops below a fixedpredetermined value, the auxiliary pump 25 automatically starts in orderto correct this pressure difference by delivering compressed air to theintake side of the pump II.

When the pressure on the intake side of the pump II exceeds thepredetermined value, the auxiliary pump automatically starts in order tocorrect this pressure difierence, by sucking compressed air from theintake side of the pump II and delivering it into the atmosphere.

When the pressure on the discharge side of the pump II drops below apredetermined value corresponding to the actual position of theregulating screw nut N of the manometric device I01, the motor I43automatically starts up in order thereby to displace the cams (Fig. 4)in the direction corresponding to an increase in the admission, inrelation to the stroke of the piston, which in its turn tends to correctthe difference in pressure which caused the motor I48 to come into play.

When the pressure on the discharge side of the pump II exceeds the valuecorresponding to the ment I44 is of the type known per se comprising amovable member, moving it accordance with the temperature, and can beplaced for instance in the place to be heated or cooled (that is to say,the chambers or compartments I5, I6, I1), or it can be caused to be incontact with the circulating fluid at a chosen point in the latterscircuit. Generally speaking, it reacts in accordance with the heating orthe cooling produced by the apparatus.

The function of the thermostat element I44 is to cause an automaticincrease in the radio between the discharge and intake pressures of thepump, when the heating or cooling produced by the installation becomesinsuflicient, and in order to produce a decrease of this ratio, if theheating or cooling effect produced becomes excessive.

The function of the control member I is to enable the desiredtemperature to be predeterelement below the predetermined value (or moreexactly below the minimum limit fixed) whereas an insuflicient coolingcauses this value (or the maximum limit fixed) to be exceeded.

The control member I45 comprises a series of contacts I41 electricallyinsulated from one another, and arranged in a semi-circle. It moreoveralso comprises a contact I48 arranged the same distance from the centeras the contacts I41, but beyond one end of the semi-circle formed by theseries of contacts I 41. This contact I48 is connected by a lead I49 toone terminal of the relay I3I, the other terminal of the relay I3I beingconnected to the main I35. A similar contact I50 is arranged beyond theother extremity of the semi-circle formed by the series of contacts I41.The contact I50 is connected by a lead I5I to one terminal of the relayI32, the other terminal of the relay I32 being connected to the mainI36. An electrically conductive segment I52 slightly less than asemi-circle rests upon the contacts I41. This segment I52 ismechanically connected with a similar se ment I53 by means of aninsulated piece I54, which is rigidly connected to a handle I55 providedwith an index I56, adapted to be displaced relatively to a scale I51.The segment I53 also rests on the contact I41. If the handle I55 beturned the two conductive segments I52 and I53 turn with it around thecentre of the semi-circle formed by the contacts I41. According to theposition occupied by the handle I55 and the index I56, certain contactsI 41. (the first ten from the left in the drawing) are connected to thecontact I48 by means 01 the segment I52, whereas others (the firstthirteen on the right, for the position shown in the drawing) areconnected to the contact I50 by means of the segment I53.

In the interval comprised between the two free ends of the segments I52and I53, there remains a small number oi contacts (the 11th and the 12thfrom the left, in the embodiment shown in the drawing) which are notconnected electrically either to contact I48 or to contact I50. Aconductive segment I58 of slightly more than a semi-circle, is arrangedconcentrically to the are formed by the contacts I41, I48 and I50. Thesegment I58 starting from the lower radial edge of the contact I48extends to the lower radial edge of the contact I50. A movable brush I59is mounted on an arm I60 which is pivotally mounted at the common centreof the segment I58 and of the semi-circle formed by the contact I41. Thebrush I59 electrically connects the segment I58 with the contacts I41 bycontact therewith. The brush I59 slides over the segment I56 and overthe series of contacts- I41 when the arm I60 is turned. The segment I58is connected to the main I35 by means of a lead "II. The arm I60 isprovided with a pointer I62, which moves over a graduated scale I63. Thearm I 60 is rigidly mounted on a spindle I64 which is caused to rotateby the motion of a rack I55 transmitted to it by means of speedincreasing gears I66. The rack I65 is fixed to the moving member of thethermostat element I44. Movement of the rack I65 is brought about by achange in temperature reflected by movement of the thermostat elementI44. In turn, movement of the rack I65 causes, through the mechanismdescribed, a corresponding movement of the brush I59 and of the pointerI62. The scale I63 is so calculated that the pointer I62 directlyindicates the temperature corresponding to the position of the movablemember of the thermostat element I44.

In Figure 10 it will be observed that, if the reversing switch I45 be inthe position shown which corresponds to the case of heating and theindex I56 is moved into any desired position in relation to the scaleI51, the brush I59 may be in contact either with one of the contacts I41touched by the segment I52 or by the segment I53, or with one of thecontacts I41 which is touched neither by the segment I52 nor by thesegment I53. When the brush I59 is in contact with any one of thecontacts I41 which is then connected to the contact I48 by the segmentI52, the relay I3I is excited by closing the following circuit: mainI35, conductor I6I, segment I58, brush I59, contact I41 in contact withthe said brush, segment I52, contact I48, conductor I49, relay I3I tomain I36. The relay I32 is then inoperative. When the brush I59 is incontact with any one of the contacts I41 which is connected to thecontact I50 by means of the segment I53, the relay I32 is energized byclosure of the following circuit: main I35, conductor I6I, segment I58,brush I59, contact I41, at the time in contact with the said brush.segment I53, contact I50, conductor I5I, relay I32 and main I36. Therelay I3I is then inoperative. When the brush I59 is in the positionshown in Figure 10, where it is in contact with some of the contacts I41which are touched neither by the segment I52 nor the segment I53, thenboth the relays I3I and I32 are inoperative, their energizing circuitsbeing open. If by reason of a variation of the temperature of the locusor place in which the thermostat element I44 is placed, the brush I59moves in a clockwise direction, from the position shown in Figure 10, toa sufiicient amount to come into contact with a contact I41 that istouched by the segment I53, then the relay I32 is instantly energized.It will only become dead at the moment when the brush I59 has returnedto one of the contacts I41 not touched by the segment I53. If, on thecontrary, the variation of temperature in the place or locus wherein thethermometric element I44 is placed be such that the brush I59 movesanti-clockwise from the position shown, by a suflicient amount to comeinto contact with one of the contacts I 41 touched by the segment I52,then the relay I 3! becomes instantly energized the moment the saidbrush touches the first of .the said contacts. The relay I3I will godead the instant the brush I59 breaks contact with one of the contactsI41 touched by the segment I52.

This distance between the free ends of the segments I52 and I53determines the scale of the admissible temperature, that is to say, themargin tolerated on both sides of the fixed value, and the fixed valueis determined by the position of the index I56 in relation to the scaleI51.

From the foregoing it will be understood that when the reversing switchI46 is in the position for heating (the position shown in Fig, 10) anincrease in the temperature at the thermostat device exceeding thetolerance above the fixed value gized. When the said reversing switch isin the position for cooling, the same increase in temperature causes therelay I3I to become energized.

Similarly, a decrease in temperature produces the excitation of therelay I 3I in the case of heating and of the relay I32 in the case ofcooling or refrigeration. It has already been stated that the excitationof the relays I3I and I32 by means of the motor I29, the worm I20, theworm wheel 9 and the nut causes a modification of the regulation of themanometric device I01. The action of the relay I3I is to displace theregulation or adjustmentitowards the higher pressure, that of the relayI32 is the reverse. Thus, an increase of the difference between thedischarge pressure and the intake pressure of the main pump'increasesthe heating, or the cooling effect produced by the apparatus. Areduction of the said difference produces the opposite effect. Inconsequence, the regulating devices shown in Figure 10 will constantlytend to correct the excess and the insufficiencies of the heating andthe cooling.

The reversing switch I 46 is preferably made mechanically integral orrigid with the multiple way plug cook 23 (Fig. 1), in order that bysimply moving the handle 24 it shall cause at the same time both theplug cook 23 and the reversing switch I46 to pass from the heatingposition (shown) to the cooling position. The operation of the apparatuswill now be described, after briefly indicating how to start theapparatus working. i

55 This Operation on starting the apparatus To start the apparatus, themultiple way plug cock handle 24 and the reversing switch I46 are in thefirst instance moved into their proper po- 5 sition. If the apparatus berequired to heat, this cock should be in the position shown in Figure 2,and the reverser in the position shown in Figure 10. If, on thecontrary, the apparatus is to be used for cooling, then the whole unitof the eight 10 plugs of the cock 23 is turned by 45 in a clockwisedirection (as the parts appear in Fig. 2) by means of the handle 24(Fig. 1). As previously mentioned, these plugs and the switch I46 arepreferably mechanically and positively intercon-. nected in such manner,that for this new position of the multiple way cock, the switch I46shall be in its other position to that shown in Fig. 10.

This done, the apparatus can be started for exampl in the followingmanner:

At the beginning only the circuits of the electric motors 36 and I4I areclosed (Figs. 4 and 10) This is effected by closing on the one hand thecircuit, not shown, of the motor 36, and on the other hand by moving adouble commutator 25 switch I99 (Fig. 10) into a position where itconnects the terminals I39, I49 of the motor I4I to a source of currentthe mains of which are denoted by 260 and MI. The motor 36 (Figures 3and 4), then starts to rotate the shaft 48, which then drives the mainpump II and the reciprodischarge pipe II have attained the desiredvalues. Once this is obtained, the circuit of the electric motor 36 isleft closed' and the commutator switch I99 is brought back to theposition shown in Figure 10, while the mains I35, I36 shown in 40 Figure10 are energized with current from a source not shown.

From that moment onwards the apparatus The arrows shown in full lines inFigure 1 indicate the flow of circulation when the apparatus is used forheating. The working fluid in the intake pipe 10, at a pressure of from20-: to

o kg./cm. (approximately 284 to '111 lbs. per

sq. in.) or more, is compressed by the pump II until it reaches apressure double or more that -of the intake pressure, but at least equalto 35 kg./cm. (approximately 498 lbs. per sq. in.). compression,approximately adiabatic, raises the temperature of the working fluid.The working fluid issuing through the discharge pipe H from the pumppasses successively through a pipe I64, the plug passage way b (Figure2) oi. the multiple cook 23, a pipe I65,

the cook 35, and passes from there first of all into the pipe I66,thereupon respectively through the pipes I61, I68 and I69 to theradiators I2, I3 and I4. In these radiators the working fluid gives upheat to the chambers or compartments I5, I6 or I1 at an approximatelyisobar rating or regime. Its temperature thus drops. The working fluidleaves these radiators respectively 70 through the pipes I10, HI andI12, then passing 7 leading to the heat exchanger 22. The working fluidpasses out of the heat exchanger 22 through a pipe I18 and then flows tothe plug way as at d via a pipe I11; it leaves this plug by means of apipe I18 leading it through the pipe 12 to the compressed fluid motor28. The

fluid then expands approximately adiabatically in this motor, inproducing work, which can be recovered and utilized to drive the saidpump II. During that expansion the temperature of the fluid dropscorrelatively. The fluid leaving the motor 28 at 13 passes on to theplug as at e .by means of a pipe I18. It leaves the plug to pass througha pipe I88 leading it to the fluid reheater I8 or heat absorber. Inpassing through this reheater, the fluid which is then at a lowertemperature than that in which the reheater is placed (the atmosphere inthe case of a railway carriage or truck), absorbs heat from the ambientmedium at an approximately isobar regime. In the case of stationarystructures, the coil I8 may be immersed in running water, in a lake,etc. The working fluid issuing from the reheater I8 then passessuccessively through the following parts: a pipe I8I, a pipe I82, theplug 23 as at I, a pipe I83, a pipe I84, the heat exchanger 2I, a pipeI85, a pipe I88, the plug as at a from which the fluid issues into apipe I81 which leads the fluid back to 18.

Then the cycle of the working fluid recommences.

While the working fluid describes its cycle, the fans 33 and 34circulate ventilating air into the chambers or compartments I5, I8 orI1. The fan 33 takes air from the outside atmosphere through the inletI88, provided at one end of the heat exchanger 22. The air, thus suckedin, passes through the heat exchanger 22, to reach, at its other end,the inlet of the pipe I88 through which it flows to the plug as at gfrom whence it emerges via a pipe I88 to the fan 33 and flows from thereto a pipe I9l, at which point it is distributed to the three air inlets21, 28 and 28 via the pipes I8I', I82 and I83 respectively.

The fan 34 draws the vitiated air from the chambers or compartments I5,I8 and I1 through the funnels 38, 3I and 32. The air thus drawn isdelivered to the fan 34 by the pipe I84. The fan 34 forces this air intoa pipe I85 from whence it then passes through the plug as at h to a pipeI88 leading it to the heat exchanger 2| at the end opposed to its outletI81 from where this air escapes into the atmosphere.

It will be noted, that the air, at the surrounding temperature sucked inat I88, circulates in the exchanger 22 in counter-current flow to theworking fluid. It thus abstracts heat from the working fluid, before thelatter expands in the motor 28, so that this air arrives at the openings21, 28 and 28 at a temperature higher than that of the outside air. Whenit emerges from these openings the air of aeration circulates incounter-current flow to the working fluid flowing through the radiatorsI2, I3 and I4, so that it is further heated. It is this aeration-airthat is thus twice heated that penetrates into the chambers orcompartments I 5, I8 and I1.

The vitiated air withdrawn at 38, 3I and 32 is at a higher temperaturethan that of the outside atmosphere, so that when it subsequently passesinto the exchanger 2I in counter-current flow to that oi the workingfluid, it gives up heat to the working fluid when the latter is at itslowest. temperature immediately before it is to be intaken by the pumpII to be comp there.

This circulation of the air of aeration of the places to be heated, incounter-current flow through the exchangers 2| and 22 causes, apart fromother heating of the air sent into these places, a heating of theworking fluid while the latter is at a low temperature prior to itscompression, and also a cooling of this working fluid before itsexpansion. This is an important feature of the invention because it ispossible to show that the mechanical efliciency of the cycle is improvedby using the greatest possible differences of volume. This heating priorto the compression of the working fluid, and its cooling after expansionhave precisely the effect to fulfill this condition by an exchange ofheat between the working fluid and the medium surrounding the place tobe heated.

It is possible to decrease the degree of heating in the chambers I5, I6and I1 by bleeding a part of the working fluid off across the by-passI88, so that a smaller quantity of this fluid passes through theradiators I2, I3, I4 per unit of time This bleeding is effected byturning the plug cock 35 anti-clockwise (as seen in Figure 1) in orderto partially cover the entry to the pipe I88 and at the same timeprogressively to uncover the entry to the by-pass I88 while at the sametime leaving the outlet of the pipe I full open.

If the pressure at the intake side of the pump II deviates from thedesired value for which the bolt II5 (Figure 8) has been set, thecommutator switch I22 acts automatically, as previously explained, inorder thereby to cause the motor I4I to start up and to drive theauxiliary pump 25 in order to increase or decrease the pressure inintake pipe 18 and thus re-establish the desi ed pressure there.

If the pressure at the discharge side of the main pump l I deviates fromthe value corresponding to the actual adjustment of the bolt I I5(Figure 9) the commutator switch I22 acts automatically, as previouslyexplained, and causes thereby, by means of the motor I43 he worm I 82and the worm wheel I8I, a variation of the degree of advance of theadmission valves such that the proper re-establishment of a suitablepressure in discharge pipe 1I automatically ensues.

Let it be assumed that, the apparatus functioning normally, the indexI38 (Figure 10) is moved over a temperature (on the scale I51) above themedium in which the thermostat device I44 is placed, and whichcorresponds to the position of the hand I82 on the scale I83. This meansthat the apparatus must supply more heat. In order to obtain thisadditional heating, it suflices to increase the difference between theintake and discharge pressures of the main pump. In the arrangementshown, this increase is effected by acting on the discharge pressureonly in the following manner. Since the temperature at thermostat I44 isless than the desired temperature (that is to say than thatcorresponding to the position of the index I58) the brush I58 is on oneof the contacts I41 in contact with the segment I52. Consequently therelay I3I is energized as hereinbefore explained, whereby the bolt 5' isdisplaced thus shifting the adjustment of the manometric device I81towards a higher pressure.

If the rod III were in the position shown in Figure 10 before thedisplacement of the nut II 5', then while bolt 5' is being unscrewed rodIII' undergoes a displacement in a direction which causes the closing ofth contacts I21 and I28 by the commutator switch I22. The result is thatthe electric motor I43 starts to rotate and 3,310,520 causes the wormwheel IM to be displaced in a direction corresponding to an advance inthe admission valves of the pump I I, as previously mentioned. Thisadvance'in the opening of the valves causes a tendency to increase thepressure in discharge pipe H, which brings about the desired increase ofthe difference between the discharge and the intake pressures of thepump. Once the new higher discharge pressure is attained, the commutatorswitch I22 returns and'automatically to the position shown, at which themotor I43 stops. The consequence of this increase in pressure is anincrease in the heating produced by the apparatus so that the thermostatdevice I44 indicates an increase of temperature, which causes the brushI59 to move in a clockwise direction as seen in Figure 10. When thebrush I 59 arrives at such position that the hand I 62 is opposite avalue (on the scale I63) which is substantially equal to the value (onthe scale I51) indicated by the index I56 at the time, the brush I 59will then be in contact with one of the contacts I41 that is not touchedby the segment I52. From that instant onward" the relay I3I comes torest as previously explained, thus stopping the motor I29. This stoppingof the motor I29 also immobilizes the bolt I I5.

When, by reason of the advance of the admis sion, the pressure indischarge pipe H has attained a value corresponding to the position inwhich the bolt II5 stopped, the commutator switch I22 opens and themotor I43 stops. From that moment onward the variations in temperature,which can be detected by the thermostat element I94, cause the relay I3Ito act automatically if it concerns a lowering of temperature, or therelay I32 if it concerns an increase of temperature. Thus, theadjustment of the manometric device I01 may be automatically modified tobring about a variation of the discharge pressure in pipe II in adirection corresponding to a correction of the diflerence of temperaturein question. This modification of the adjustment of the device I01causes the motor I43 to start in a direction corresponding to avariation of the admission, by displacement of the cams in thecorresponding direction. If the thermostat I 44 detect a drop oftemperature, the admission will be advanced in such manner as tore-establish the desired temperature. If, on the contrary, it detect anincrease of temperature, the admission will be retarded.

It will be understood therefore that the regulating arrangementaccording to Figure permits at any time during the working of theapparatus, predetermining th temperature it is desired to have in theplace where the thermostat device I44 is located, and automaticallyobtaining the necessary modifications of the regulation necessary toeffect and maintain this temperature.

Operation when used for cooling The arrows indicated in Figure l indotted lines clearly indicate the direction of the circulation when itis desired to eifect cooling.

The working fluid arriving at intake pipe 10 at a pressure of 25 to 50kg./cm. or more, is compressed by the main pump II to say double thatpressure or more. This compression, approximately adiabatic, raises thetemperature of the working fluid. At the pump delivery at 1!, theworking fluid passes successively through the following parts: the pipeI64, the plug passage b, a pipe 202, the pipe I8I, the heat exchangerl9, which in this case acts as a radiator. By

reason of. the passage of the fluid through this radiator, the workingfluid is subjected to a drop in temperature approximately according tothe isobar regime. The fluid leaving the radiator I9 flows successivelythrough the pipe I90, a pipe 203, the plug way c (Figures 1 and 2), apipe 204, a. pipe I16, the heat exchanger 22, the pipe I15, a pipe 265,the plug way'd and the pipe I18, which leads it at I2 to the workingfluid motor 20. In this motor the fluid expands approximatelyadiabatically, giving out mechanical work which is recovered and servespartially to drive the main pump II. The fluid leaves the motor at 13 ata low temperature and reaches the pipe I19 which leads it to the plugway e whence it leaves by the pipe 206 to pass then successively throughthe pipe I65, th plug cock 35 and the pipe I66, from where it flows tothe three heat exchangers I2, I3 and I4, through the pipes I61,

I68 and I 69 respectively. These heat exchangers act then as reheatersoi the fluid in absorbing heat from the chambers I5, I6 and I1 which arethus cooled. The working fluid leaves these reheaters I2, I3, It bymeans of the pipes I19, I" and I12 respectively, and then arrives in apipe I13 to pass then successively through a pipe 201, the plug way i,a, pipe 208, the pipe I85, the heat exchanger 2|, the pipe I86, a pipe209, the plug way a and the pipe I81, thus returning the fluid to 10 torecommence the cycle.

While the working fluid describes this cycle, the fans 33 and 36circulate the air required for aeration. The fan 33 draws in fresh airfrom the outside atmosphere through the mouth I91 of the heat exchanger2 I.

This fresh air flows successively through the pipe I96, through the plugway h into a pipe 2I0, into the pipe I leading to the fan 33 from whichit is forced into the pipe I9I thus reaching the mouths 21, 28 and 29,via the pipes I 9I, I92 and I93 respectively.

The fan 34 sucks the vitiated air out of the chambers or compartmentsI5, I6 and I1 through the funnels 30, 3| and 32. The air thus withdrawnis led to the fan 34 by the pipe I94. After having passed through thisfan, the air is. forced successively through the following parts: thepipe I95, a pipe 2, the plug way 9, the pipe I89 and the heat exchanger22 through the opening I88 of which it escapes into the atmosphere.

It will be observed that the air at the surrounding temperature, drawnin at I 91, circulates in the heat exchanger 2I in counter-current flowrelatively to the working fluid. It therefore gives up heat to thatfluid, so that the air arrives at the openings 21, 28 and 29 at a lowertemperature than that of the outside air. When leaving these openingsthis air circulates in counter-current flow relatively to the flow ofthe working fluid passing through the reheaters I2, I3 and I4, so thatit continues to cool down. In this manner cool, fresh air is circulatedinto the chambers or compartments I5, I6 and I1.

The vitiated air withdrawn at 30, 3| and 32 is at a temperatureintermediate between that of the external atmosphere and that of theworking fluid arriving at the reheaters I2, I3 and I4 as it leaves themotor 20, so that when the vitiated air subsequently passes into theexchanger 22 in counter-current flow in respect to the working fluid itwithdraws heat from the fluid flowing to the motor before being itselfexpelled into the atmosphere.

This circulation of ventilating air at the places to be cooled, incounter-current flow through the exchangers 2| and 22 has th eflect orproducing, beside a pre-coolingof the air delivered into these places, are-heating of the working fluid before its compression, as well as acooling of this working fluid before its expansion. The same advantagesare therefore obtained in the case of cooling as have alreadybeenmentioned in the case of heating, viz: an increase of the differencebetween the extreme specific volumes of the fluid in the course of itscycle.

The degree of cooling in the chambers I5, II and II can be diminished bybleeding a part of the working fluid off through the bypass pipe I98, bythe cook 35, so that a lesser quantity of this fluid passes through thereheaters l2, I3 and I4 per unit of time.

If the pressure on the intake side of the main pump II varies from theflxed value, the desired pressure will be automatically re-establishedin the same manner as in the case of heating, by

means of manometric device I05 and the aux-.

iliary pump 25. a

If the pressure on the discharge side of the main pump ll deviates fromthe value corresponding to actual adjustment of the bolt 5', the properpressure will be automatically reestablished by a variation of theadmission under the control of the manometric device I01.

If, when the apparatus be working normally, the index I55 (Figure isdisplaced opposite to a temperature indication on the scale I51,different to the temperature shown by the thercase of an installationfor the production of heat or cold according to the principle of thethermo-pump, to have as high a mechanical efflciency as possible of themachines used in the apparatus. It is for 'this reason that areciprocating pump and a motor with pistons using a compressed fluidhave been usedin the embodiment described, because, it is only with thistype of machine that it is possible to obtain very high mechanicalefllciencies.

In order to reduce the losses, it is preferable to provide needlebearings for the connecting rods.

mostat device I, which is indicated by the position of the pointer I52on the scale I63, then there will follow an automatic variation in asimilar manner as described in the case of heating, of the differencebetween the extreme pressures of the cycle in the sense corresponding toan increase or decrease of the cooling, according as to whether thetemperature at I shall drop or rise. Once the desired temperature isthus obtained, it is automatically maintained in the same manner aspreviously described in the case of heating.

If it be assumed, for instance, that it is desired to obtain at I ahigher temperature than that obtaining, that is to say, if it benecessary to reduce the cooling, then the handle I55 is turned clockwiseto the extent desired. There automatically follows the energization ofthe relay I3I the starting up of the motor I29, a variation of theadjustment of the manometric device IDI follows in the sense of adecrease of the difference of pressure. This modification of theregulation causes the motor I43 to start up in the sense of retardingthe admission which tends to lower the pressure inpipe II, Once thepressure at II has dropped, the temperature at I increases and thepointer I62 tends to move to the position corresponding to the desiredtemperature. Once this position is attained, the relay I 3| isde-energize'd, and the motor I29 stops. When the desired pressure at IIis thus attained, the motor I43 stops in its turn and, from that momentonward, the desired temperature will be automatically maintained at I ina similar manner as has previously been described in the case ofheating.

In case of unduly high pressure, the automatic safety valve 2I2 (Figure1), comes into action and allows the working fluid to escape, eitherinto the atmosphere, or into a reservoir connected to the auxiliary pump25 at 25.

It is of the very greatest importance, in the In the case where theintake and discharge pressures used are of the order of 50 and kg./cm.(approximately 711 and 1138 lbs. per sq. in.), respectively, the pistonrings will work at a difference of pressure of 30 atm. which is of thesame order as those maximum pressures used in explosion motors. It wouldtherefore be possible to use ordinary piston rings. If it be desired touse extremely high pressures, for example, and 160 kg./cm.=(approximately 1422 and 2275 lbs. per sq. in.), respectively, it wouldthen be of advantage to provide on the exterior. face of the piston afluid at the medium pressure, say kg./cm. (approximately 1850 lbs. persq. in.) so as not to increase the difference of pressure under whichthe piston rings work. In this case, the circuit of the working fluidwould no longer pass through the gear box or boxes of the main pump andof the reciprocating motor. For still higher pressures between the twofaces of the piston, care would have to be taken to use a solutionwhich, while making sure of an effective fluid tightness, does not lead1 to exaggerated losses by reason of too great friction. It would thenbe preferable, instead of v ordinary piston rings, to use packings ofthe type described in the French Patent No. 632,537 of the 9th of April,1927. The same kind of fittings may also be employed with advantage toensure fluid tightness to the different stages of the multiple way plugcook 23 and the cook 35,

The packing in question consists, in general, of one or several sheetsof a substance such as a photographic or cinematographic film, ofnontanned veal hide or of some other suitable animal hide, vegetableparchment, or similar substance other than metal or leather, of aflexible but yet still. nature, the said packing, when it is in workingposition and is composed of a plurality of cells, presenting a hollowedout central and conical part, directed in the direction in which the gasor the liquid exerts its high pressure.

The arrangements indicated, wherein the members ensuring fluid tightnessof the pistons are only subjected to the difference or half thedifference between the low and the high pressure of the cycle, cooperateto minimize the mechanical efforts, and correlatively the frictionswhich depend on the former are thus reduced and the efllciency improved.

It is obvious, that instead of combining the main pump and thecompressed fluid motor into a single unit, it would be possible toprovide a pump and a reciprocating motor quite distinct and apart fromone another.

The springs of the valves provided are made as weak as the necessity ofinertia permit, in order that:

1. The loss of energy from the fluid during its passage through thecylinders of the pump may be as small as possible.

2. In case of an unduly high pressure arising in the motor (caused, forexample. by improper regulation of the admission and exhaust valves),the forcing back of the fluid will take place against a weak backpressure, that is to say, with as small a lossof energy as possible, thesame thing happening in the case of the partial vacuum during thesuction.

In order to reduce the losses, it would be possible to use for the pump,in the example Just described as well as in the modification which hasJust been indicated, not automatic valves of admission and compression,but valves controlled and actuated in an exactly similar fashion to thatindicated for the motor. In this case the regulation of the pressurescould still be eiposite sense.

The connecting rods could be different to those shown in the drawings.They might in particular be similar to those described in the FrencliPatent No. 437,491 of the 12th of December, 1911. According to thispatent, there is provided at the extremity of the connectin g; rod aspherical supporting surface having the aspect of a parallelogram,limited by four lateral faces two and two in parallel, of whichv two arein the planes perpendicular to the axis of the crank pin, and the twoothers oblique, a guiding member being placed above the contact surfacealso presenting four lateral faces, two and two in parallel, of whichtwo also have their plane perpendicular to the axis of the crank pin theother two beingoblique in a sense different to the oblique phases of thesupporting surface. In this design a ring or annular member of contactwith spherical surface is provided, upon which the different connectingrod feet which are maintained on this annular member by lateral cheekswith ledges rest, against which ledges the lateral supporting faces onthe contact surface of the connecting rods which form the guide memberrests, in order to form reaction couples opposed to the rotation of theconnecting rod around its shaft.

In practice it will be of advantage to provide means known per se toremove automatically by scraping any hoar frost that might form on thereheating member for the fluid IS, in the case of heating. In the caseof cooling or refrigerating, care must be taken, that the heatexchangers i2, I3 and M, which then function as fluid reheaters do notfall below a temperature of C., so as to avoid the formation of frost.This can be effected, either by means of a thermometer with electriccontact, acting in a manner known per se on a valve such as the valve 2l2, in order to cause the high pressure to drop and consequently reducethe cooling effect, when the low temperature of the working fluid dropsbelow a minimum previously fixed, or in limiting the path of the handleI55 (Figure on the side of the low temperatures.

The reheaters I2, l3 and M will be arranged preferably in such manner asto permit any condensate of water forming thereon to drain oil.

In the exampledescribed the regulation of the heating and the cooling iseffected by only varying the discharge pressure of the main pump in suchmanner as to increase or decrease the difference between the extremepressures of the cycle, and consequently the ratio of these pressures.It is evidently possible ,to act in a similar manner as regards theintake pressure only, or to vary the intake and discharge pressures ofthe cycle simultaneously. I

Instead of using air it would be possible to use other gases especiallya monoatomic gas. The monoatomic gases have the remarkable advantage,that they permit of a substantial reduction of the compression ratios.It must moreover be pointed out here, that'it will be advantageous, withthe apparatus described, to work with high pressures but with moderatecompression ratios.

The high pressure of the cycle through which the working fluid is madeto pass is preferably comprised, in case a gaseous fluid is concerned,between 35 and several hundreds of kg./cm. The ratio of high to lowpressures to which the working gaseous fluid is subjected is preferablyat the most equal to 3; it will be still more preferably of the order offrom 2 to 2.5.

The ultra turbulent regime, of which mention has been made above, andwhich allows of increasing to a very great-degree the rapidity of theexchange of heat between the working fluid and the walls, can be easilyobtained by giving the wall in contact with the fluid a rough surface,by threading it for instance.

I claim:

1. The process of regulating the temperature of the air within anenclosed space, comprising maintaining a non-condensing gas in thecrankcase of a compressor at a pressure not substantially lower than 20kg./cm., drawing gas from said crankcase into the cylinders of saidcompressor, compressing said gas in said cylinders to a pressure notsubstantially in excess of 2.5 times the pressure maintained in thecrankcase, restraining the flow of heat from the gas in said cylindersby thermal insulation on the cylinder heads and pistons of saidcompressor, subjecting gas discharged from said cylinders to heatinterchange to abstract heat therefrom, thereafter expanding said gas ina gas-expansion motor adapted to furnish a part of the power required todrive said compressor, subjecting gas expanded in said motor to heatinterchange to supply heat thereto, and introducing air whosetemperature is to be regulated into one of said heat interchangers.

2. The process of regulating the temperature of the air within anenclosed space, comprising maintaining non-condensing gas in thecrankcase of a compressor at a pressure not substantially lower than 20kg./cm. drawing gas from said crankcase into the cylinders of saidcompressor, compressing said gas in said cylinders to a pressureapproximately two and not substantially more .than two and one-halftimes the pressure maintained in the crankcase, restraining the flow ofheat from the gas in said cylinders by thermal insulation on thecylinder heads and pistons of said compressor, subjecting gas dischargedfrom said cylinders to heat interchange to abstract heat therefrom,thereafter expanding said gas in a gas-expansion motor adapted tofurnish a part of the power required to drive said compressor,subjecting gas expanded in said motor to heat interchange to supply heatthereto, returning said expanded gas to said crankcase and introducingair whose temperature is to be regulated into one of said heatinterchangers. I

3. The process of regulating the temperature of the air within anenclosed space, comprising maintaining a non-condensing gas in thecrankcase of a compressor at a pressure not substantially lower than 20kg./cm.= and approximately 25 kg./cm., drawing gas from said crankcaseinto the cylinders of said compressor, compressing said gas in saidcylinders to a pressure approximately two and not substantially morethan two and one-half times the pressure maintained in the crankcase,restraining the flow of heat from the gas in said cylinders by thermalinsulation on the cylinder heads and pistons of said compressor,subjecting gas discharged from said cylinders to heat interchange toabstract heat therefrom, thereafter expanding said gas in a gasexpansionmotor adapted to furnish a part of the power required to drive saidcompressor, subjecting gas expanded in said motor to heat interchange tosupply heat thereto, and introducing air whose temperatureis to beregulated into one of said heat interchangers.

4. The process of regulating the temperature of the air within anenclosed space, comprising maintaining a non-condensing gas in thecrankcase of a compressor at a pressure substantially higher than 20kg./cm. drawing gas from said crankcase into the cylinders of saidcompressor, compressing said gas in said cylinders to a pressureapproximately two and not substantially more than two and one-half timesthe pressure maintained in the crankcase, restraining the flow of heatfrom the gas in said cylinders by thermal insulation on the cylinderheads and pistons of said compressor, subjecting gas discharged fromsaid cylinders to heat interchange to abstract heat therefrom,thereafter expanding said gas in a gas-expansion motor adapted tofurnish a part of the power required to drive said compressor,subjecting gas expanded in said motor to heat interchange to supply heatthereto, and introducing air whose temperature is to be regulated intoone of said heat interchangers.

5. In apparatus for maintaining a desired temperature in the atmosphereof an enclosed space, in combination, a combined gas compressor and gasexpansion motor having an even number of cylinders not less than sixradially and equiangularly disposed about a crankcase, the cylindersbeing so arranged that alternate cylinders form part of the compressorand intervening cylinders form part of the motor, pistons withheatinsulated heads mounted in said cylinders and connected to a commoncrank, means for conducting a non-condensing gas in a cyclic pathincluding in the order stated the compressor, a first heat interchanger,the motor, and a second heat interchanger, and means for passing acurrent of the air whose temperature is to be maintained through one ofsaid heat interchangers and to discharge the same therefrom into theatmosphere of the enclosed space.

6. In apparatus for maintaining a desired temperature in the atmosphereof an enclosed space, in combination, a combined gas compressor and gasexpansion motor having an even number of cylinders not less than sixradially and equiangularly disposed about a crankcase, the cylindersbeing so arranged that alternate cylinders form part of the compressorand intervening cylinders form part of the motor, pistons withheatinsulated heads mounted in said cylinders and connected to a commoncrank, means including spring-held valves positioned in the heads of thepistons mounted in the compressor cylinders for conducting anon-condensing gas in a cyclic path including in the order stated thecompressor, a first heat interchanger, the motor, and a second heatinterchanger, and means for passing a current of the air whosetemperature is to be maintained through one of said heat interchangersand to discharge the same therefrom into the atmosphere of the enclosedspace.

7. In apparatus for maintaining a desired temperature in the atmosphereof an enclosed space, in combination, areciprocating gas compressor anda reciprocating gas expansion motor, each having pistons and cranksconnected to a common crankshaft, an enclosed crankcase for saidcrankshaft, means for conducting a non-condensing gas in a cyclic pathincluding in the order stated said enclosed crankcase, the cylinders ofsaid compressor, a first heat interchanger, the cylinders of said motorand a second heat interchanger, means to maintain the compressible gasin said crankcase at a desired superatmospheric pressure, and means forpassing a current of the air whose temperature is to be main- .tainedthrough one of said heat interchangers and to discharge the sametherefrom into the atmosphere of the enclosed space.

8. In apparatus for controlling the temperature of an enclosed space, incombination, a multi-cylinder gas compressor and a multi-cylinder gasexpansion motor, their cylinders having pistons connected with a commoncrank-shaft, means for conducting a non-condensing gas in a circuitincluding said compressor and said motor, valves governing admission ofthe fluid to and its exhaust from the cylinders of said compressor andmotor, a valve-actuating cam for opening and closing at least one ofsaid valves in timed relation to the movement of the piston in one ofsaid cylinders, and automatic means mutually responsive to change in thepressure of the gas at one point in its circuit and to change in thetemperature of said enclosed space for varying the time relation betweenthe operation of said valve-actuating cam and the movement of saidpiston.

9. In apparatus for controlling the temperature of an enclosed space, incombination, a multi-cylinder gas compressor and a multi-cylinder gasexpansion motor, their cylinders having pistons connected with a commoncrankshaft, means for conducting a non-condensing gas in a circuitincluding said compressor and said motor, valves governing admission ofthe gas to and its exhaust from the cylinders of said compressor andmotor, a valve-actuating cam for opening and closing at least one ofsaid valves in timed relation to the movement of the piston in one'ofsaid cylinders, and automatic means responsive to change in the pressureof the gas at one point in its circuit for varying the time relationbetween the operation of said valve-actuating cam and the movement ofsaid piston.

10. In apparatus for controlling the temperature of an enclosed space,in combination, a multi-cylinder gas compressor and a multi-cylinder gasexpansion motor, their cylinders having pistons connected with a commoncrankshaft, means for conducting a non-condensing gas in a circuitincluding said compressor and said motor, valves governing admission ofthe gas to and its exhaust from the cylinders of said compressor andmotor, valve-actuating cams for opening and closing at least one of thevalves associated with each of said motor cylinders in timed relation tothe movement of the pistons in said cylinders respectively, andautomatic means responsive to change in the pressure of the gas at onepoint in its circuit for varying the time relation between the operationof said valve-actuating cams and the movement of said pistons.

11. In apparatus for maintaining a desired temperature in the atmosphereof an enclosed space, in combination, a combined reciprocating gascompressor and reciprocating gas e nsion motor having an even number ofcylinders not less than six radially and equi-angularly disposed aboutan enclosed crankcase, alternate cylinders serving as the compressor andintervening cylinders serving as the motor, means for conducting anon-condensing gas in a cyclic path including in the order stated saidenclosed crankcase, the cylinders of said compressor, a first heatinterchanger, the cylinders of said motor and a second heatinterchanger, valves governing admis sion of the fluid to and itsexhaust from the cylinders of said compressor and motor, avalve-actuating cam for opening and closing at least one of said valvesin timed relation to the movement of the piston in one of saidcylinders, and means mutually responsive to change in the pressure ofthe gas at one point in its path-and to change in the temperature ofsaid enclosed space for varying the time relation between the operationof said valve-actuating cams and the movement of said piston.

12. In apparatus for controlling the temperature of an enclosed space,in combination, a multi-cylinder gas compressor and amulti-cylinder gasexpansion motor, their cylinders having pistons connected with a commoncrankshaft, means for conducting a non-condensing gas in a circuitincluding said compressor and I said motor, valves governing admissionof the gas to and its exhaust from the cylinders of said compressor andmotor, a valve-actuating cam for opening and closing at least one ofsaid valves in timed relation to the movement of the piston in one ofsaid cylinders, means responsive to change in the temperature of saidenclosed space for varying the time relation between the operation ofsaid valve-actuating cam and the movement of said piston, and pump meansresponsive to reduction in the pressure of gas in said circuit tointroduce fresh supplies of gas into said circuit.

13. In apparatus for controlling the temperature of an enclosed space,in combination, a multi-cylinder gas compressor and a multi-cylinder gasexpansion motor, their cylinders having pistons connected with a commoncrankshaft, means for conducting a non-condensing gas in a circuitincluding said compressor and said motor, valves governing admission ofthe gas to and its exhaust from the cylinders of said compressor andmotor, a valve-actuating cam for opening and closing at least one ofsaid valves in timed relation to the movement of the piston in one ofsaid cylinders, means responsive to change in the temperature of saidenclosed space for varying the time relation between the operation ofsaid valve-actuating cam and the movement of said piston, and reversiblepump means responsive to change in the pressure of gas in said circuitto introduce fresh supplies of gas thereto and to bleed excess gastherefrom according as the pressure falls below or exceeds a desiredpressure.

14. In apparatus for controlling the temperature of an enclosed space bymeans of a confined gas which is compressed and expanded to effect heattransfer, in combination, a cylinder, a piston working therein, a valveadapted to control the flow of fluid medium between said cylinder and aconduit connected therewith, a valve-actuating cam adapted to open andclose said valve in timed relation to the movement of the piston in saidcylinder, and means automatically .responsive to change in the pressureof said confined gas for varying the time relation between the operationof said valve-actuating cam and the movement of said piston.

15. In apparatus for controlling the temperature of the air within anenclosed space, in combination, a gas compressor and a gas-expansionmotor both operating on a common crankshaft, conduits for conducting gasat an elevated pressure from the compressor to a first heatinterchanger, then from said first heat interchanger to the motor, thenat a less elevated pressure from the motor to a second heatinterchanger, and then from said second heat interchanger to thecompressor, at least 'one of said heat interchangers being arranged toexchange heat between the said gas and a fresh supply of air passing tothe enclosed space, valves for directing the flow of gas-and of freshair respectively to S&id" heat interchangers, and common manually-operable means for simultaneously manipulating said valves to reverse thedirection of flow of gas through the interchangers and to direct theflow of fresh air through one of said interchangers when it is desiredto heat the enclosed space and through the other of said interchangerswhen it is desired to cool the same.

16. For use in transferring heat from one zone to another by means ofnon-condensing gas alternately and cyclically expanded to a pressure notsubstantially less than 20 kg./cm. and compressed to a pressureapproximately two to two and one-half times thereof in a closed circuit,in combination, a combined gas compressor and gas expansion motor havingan even number not less than six cylinders, at least a part of theinternal working surface of said cylinders being lined withheat-insulating material, said cylinders being radially andequi-angularly disposed about a common crankshaft within an enclosedcrankcase, alternate cylinders serving as the compressor for compressinggas in said circuit and intervening cylinders serving as the motorwherein gas in said circuit is expanded, means to admit gas into saidcrankcase at substantially the lowest pressure prevailing in thecircuit, spring-held valves in the heads of the pitsons operating in thecompressor cylinders adapted to govern the flow of gas from saidcrankcase to said cylinders, and a facing of heat insulating materialsecured to the working face of said pistons affording openings thereinfor the passage of gas under control of said valves.

17. In apparatus for controlling the temperature of an enclosed space,in combination, a multicylinder gas compressor and a multi-cylinder gasexpansion motor, their cylinders having pistons connected with a commonconducting a non-condensing gas in a circuit including said compressorand said motor, valves governing admission of the gas to and its exhaustfrom the cylinders of said compressor and motor, a valve-actuating camfor opening and closing at least one of said valves in timed relation tothe movement of the piston in one of said cylinders, and reversible pumpmeans responsive to change in the pressure of gas in said circuit tointroduce fresh supplies of gas thereto and to bleed excess gastherefrom according as the pressure falls below or exceeds a desiredpressure.

crankshaft, means for

